In cultivation of a variety of cells (suspension cells, adherent cells), it has been a conventional practice to replace nutrient culture medium on a regular basis. Particularly, cultivation of cells having a fast metabolism requires frequent replacement of culture medium. While cell cultivation operations including such a replacement of culture medium have conventionally been performed by experienced operators using pipettes, replacing the culture medium of a large number of cultivation containers involves a great deal of labor. More recently, automated systems for culture medium replacement operation or cultivation operation are actively developed. In such systems, solenoid valves (electromagnetic pinch valves) are commonly employed for open/close control of passages for liquid or gas. However, one solenoid valve is capable of open/close control for only one tube passage. Hence, with increase in the number of tube passages, the number of solenoid valves increases as well. This results in cost increase and complicated open/close control for multiple passages. In a case where a large number of solenoid valves are disposed in an incubator, a fear exists that the unevenness of temperature distribution in the incubator increases due to the influence of heat generated by the solenoid valves. Further, there also is a problem of increase in the cost of solenoid valves because most cultivation environments are at 37° C. in temperature and have a CO2 content of 5% and humidity of 90% or more while the solenoid valves are required of water proof property and sterilization resistance under such environments. Further, the automated cultivation systems are faced with demand for enhanced reliability in the control of tube passages by means of the solenoid.
As a prior-art technique, Japanese Unexamined Patent Application Publication No. Hei 9-303582 discloses “a multiple miniature pinch valve assembly having a structure wherein a plurality of flexible tubes through which a liquid such as chemical agent flows are retained parallel in respective grooves of a tube guide which are arranged in parallel in a lower part of a pinch valve body, a shaft is disposed orthogonally to and above the plural tubes, the shaft has a plurality of cams attached thereto, and the angle of rotation of a motor directly connected to the shaft or connected thereto via a gear or the like is controlled so as to independently open or close the respective tubes by means of the plural cams, and wherein two units including an upper casing part accommodating the cams, shaft and the driving motor therein and the tube guide define a set-in type lock mechanism which is easy to disassemble and assemble” (claim 1).
Further, Japanese Unexamined Patent Application Publication No. 2008-208879 discloses “a pinch valve comprising: a rotary body which can be rotated by a rotary shaft; a pressure member movable in response to the rotation of the rotary body; a guide for movement of the pressure member in a given direction; and a wall disposed at a position opposed to the pressure member in the movable direction of the pressure member, wherein a tube is pressed by the pressure member and the wall and the flow rate of a liquid through the tube is regulated according to the position of the pressure member” (claim 1).